1. Field of the Invention
The present teaching relates to a method for producing a liquid discharge apparatus configured to discharge liquid from nozzles, the liquid discharge apparatus configured to discharge the liquid from the nozzles, and a method for forming a liquid repellent layer by which the liquid repellent layer is formed in the liquid discharge apparatus.
2. Description of the Related Art
As a liquid discharge apparatus which discharges liquid from nozzles, there is conventionally known an ink-jet recording head which discharges ink from nozzles. In this recording head, a first insulating film is formed on the upper surface of an elastic film which is disposed to cover pressure chambers and a lower electrode film is disposed on the upper surface of the elastic film formed with the first insulating film. Further, piezoelectric films are disposed on the parts, of the upper surface of the elastic film formed with the first insulating film and the lower electrode film, overlapping with the pressure chambers, and upper electrode films are formed on the upper surfaces of the piezoelectric films. Furthermore, a second insulating film is disposed to cover the upper surface of a stacked body constructed of the elastic film, the first insulating film, the lower electrode film, the piezoelectric films, and the upper electrode films. The second insulating film is made from inorganic insulation material and has low moisture permeability. This prevents the moisture from permeating the second insulating film and reaching the upper electrode films, the piezoelectric films, the lower electrode film, and the like.
The above recording head is manufactured as follows. That is, the first insulating film, the lower electrode film, each piezoelectric film, each upper electrode film, and the like are formed on a channel formation substrate for which the pressure chamber is not yet formed, and then the pressure chamber and the like are formed in the channel formation substrate. In the recording head manufactured as described above, tensile stress or stretching stress is generated in the piezoelectric film during the formation of the piezoelectric film. The tensile stress is released when the pressure chamber is formed in the channel formation substrate to cause the force which attempts to bend the elastic film and the like so that the elastic film and the like become convex toward the pressure chamber. Meanwhile, when the second insulating film and the upper electrode film are formed, the sum of stresses generated in the second insulating film and the upper electrode film is compressive stress. The compressive stress is released when the pressure chamber is formed in the channel formation substrate to cause the force which attempts to bend the elastic film and the like so that the elastic film and the like become convex toward a side opposite to the pressure chamber. Accordingly, the above recording head can obtain the effect that the force generated by releasing the compressive stress in the second insulating film and the upper electrode film prevents the elastic film and the like from bending toward the pressure chamber. This effect can increase the displacement amount of the elastic film and the like at the time of driving a piezoelectric actuator as compared with a case in which no second insulating film is provided.